Search engine systems gather information from the Internet and present users with search results in response to queries. Conventional search engine systems perform searches based on the results' popularity and relevancy. However, sometime the results do not match the user intent of searches. For example, a user may intend to download a song “Firefly” sung by a singer “Wang Fei.” But conventional search engine systems may return links associated with insects as top ranks. To avoid this situation, many different approaches have been proposed (e.g., category searches). While important progress has been made, the existing approaches present problems, e.g., low accuracy and efficiency for Internet searching.